1. Field of the Invention
This invention relates to a semiconductor memory device, and in particular to a semiconductor memory device restoring data in a memory cell, such as Dynamic Random Access Memory (DRAM).
2. Description of the Related Art
A semiconductor memory device capable of operating at high speed is desired by the semiconductor industry. It is necessary for the realization of "high speed" to shorten the access time, that is a cycle time (TRC). The cycle time (TRC) is defined the sum of a pulse length of a row address strobe signal RAS (TRAS) and a precharging time (TRP), that is TRC=TRAS+TRP. The lower limit of TRP is defined at a value of TRC. Consequently, the realization of the shortening of TRC means the realization of the shortening of TRAS.
A conventional semiconductor memory device, for example, is disclosed in the Japanese Laid-open publication No. 60-138792, published on Jul. 23rd, 1985.